The KALI-1000 pulse power system has been used to generate single-pulse nanosecond-duration high-power microwaves from an axial virtual cathode oscillator. The typical electron beam parameters were 250 kV, 15 kA, and 100 ns, with a current density of a few hundreds of amperes per square centimeter. The shot-to-shot variation of the microwave pulsewidth was studied for various anode-cathode gaps an...
View full abstract»

This paper presents a three-dimensional (3-D) simulation of a triode-type magnetron injection gun (MIG) for a 42-GHz 200-kW gyrotron with a transverse-to-axial velocity ratio of the electron beam at 1.22 and a maximum transverse-velocity spread of 3.2%. The operating mode of the gyrotron is TE_03, and it is operated in the fundamental harmonic. The MIG has been designed by using some tradeoff equa...
View full abstract»

Recently, we have designed and built a new microwave tube; it has been given the name “Arletron.” It works in S-band, and we describe in this paper its operation. A 200-keV 1-kA annular electron beam (e-beam) is strongly bunched in a simple assembly of two pillbox cavities. The bunching occurs at the frequency of the -mode resonance of the system. An extracting cavity, inserted just ...
View full abstract»

In this paper, a ridge-loaded folded-waveguide slow-wave structure (SWS) for millimeter-wave traveling-wave tube (TWT) is presented. The theory of high-frequency characteristics, which includes: 1) the dispersion properties; and 2) the beam-wave interaction impedance of this structure, is analyzed. The theoretical results agree well with those obtained by the 3-D electromagnetic simulation softwar...
View full abstract»

A new design for an inverted magnetron is presented and modeled both analytically, using a single particle smooth bore relativistic approach, and numerically, using a massively parallel electromagnetic particle-in-cell code, Improved Concurrent Electromagnetic Particle-In-Cell (ICEPIC) code. Analysis and simulation confirm that the inverted magnetron design presented here is capable of oscillating...
View full abstract»

A folded waveguide (FW) is a promising slow-wave structure (SWS) for millimeter-wave traveling-wave tubes (TWTs) with the advantages of high power and considerable bandwidth. A novel rectangular groove-loaded FW SWS is analyzed for the purpose of gaining higher power with a smaller size compared with the normal circuit. The high-frequency characteristics, including dispersion properties and intera...
View full abstract»

The SPIDER experiment's main goal is to test the extraction of negative ions from an ITER-size ion source. It is designed to extract 1 280 negative ion beamlets and accelerate them up to a 100 kV potential. The negative ion beam at exit and the operating parameters will be carefully measured and optimized in order to match the ITER requirements for the Neutral Beam Injector (NBI) ion sources. Insi...
View full abstract»

We derive an exact formalism for calculating the space-charge fields of an electron beam inside of a perfectly conducting cylindrical pipe. The formalism utilizes a series expansion of the beam-charge and current densities in Bessel functions in conjunction with a time-dependent Green's function method to compute the exact space-charge fields due to the beam with the appropriate conductor boundary...
View full abstract»

An experimental study on the fluctuations in the instants of time and amplitudes of the peaks in the voltage, current time derivative, X-rays, and neutron signals during a 150-shot series in a 2 kJ Plasma Focus device is presented. The results show a reasonable correlation between the time of the voltage peak and that of X-ray emission, in agreement with the picture of the formation of an electron...
View full abstract»

A SiOC film made by inductively coupled plasma chemical vapor deposition at radio-frequency power of 800 W with the precursor methyltrimethoxysilane was analyzed to find out the dielectric constant that was caused by the polarization. The dielectric constant was obtained by C-V measurement using the structure of the Al/SiOC fllm/p-Si substrate. The peak shift observed in the Fourier transform infr...
View full abstract»

Physical modeling with numerical simulation is very useful for researchers to understand and improve the plasma-enhanced chemical vapor deposition process for coating of diamond-like carbon (DLC) films. In this paper, we implement a fluid model including a chemical reaction mechanism for methane plasmas. Employing a finite-difference method, we solve for the low-pressure RF plasma phase in a paral...
View full abstract»

Drived by a μs pulse high-voltage power supply, a homogeneous DBD in atmospheric air is generated between two plane-parallel electrodes, with PTFE plates as dielectric barriers. The discharge generated shows homogeneous discharge characteristics. The light emission is radially homogeneous and covers the entire surface of the electrodes, and a single current pulse with duration of about 1 s ...
View full abstract»

The plasma sporicidal effects on Bacillus atrophaeus spores were studied using a low-temperature atmospheric plasma brush in terms of the following conditions: 1) plasma conditions; 2) plasma gas compositions; 3) plasma exposure time; and 4) the types of supporting media. It was found that the plasma brush with O_2 addition was very effective in inactivating the Bacillus spores. With 0.33, 0.7, an...
View full abstract»

A toroidal field coil (TFC) is composed of several individual toroidal coils (ITCs), which are connected in series and distributed in the toroidal and symmetrical forms. This paper presents the analytical equations of mutual inductance and electromagnetic torque of the TFC that are applicable to Tokamak reactors. The analytical equations of translational forces, which are imposed on the ITCs of th...
View full abstract»

Graphite-in-diamond (GiD) nanoparticles in which the secondary-electron-emission coefficient was larger than the MgO protective film were introduced to enhance the electrical and optical characteristics in alternating-current plasma displays. The GiD nanoparticles suspended stably in ethanol solvent were sprayed uniformly on an MgO film. Based on the results of field-emission scanning electron mic...
View full abstract»

A simple and easy-to-use electric-circuit model for fluorescent lamps is deduced from experimental tests. The lamp arc is modeled as a power-dependent resistance. By incorporating the lamp model with electronic ballast, design equations for dimmable electronic ballasts using half-bridge resonant inverter are derived, and then the dimming operation characteristics can be predicted analytically. Det...
View full abstract»

Dielectric barrier discharge excitated by pulsed power is a promising approach for producing nonthermal plasma at atmospheric pressure, but pulsed power generators vary widely in performance and should be chosen according to application requirements. In this paper, a repetitive unipolar nanosecond-pulse generator is constructed using resonant charging and one-stage magnetic compression circuits, w...
View full abstract»

In this paper, a new insulation system of ZnO varistor ceramic-Al2O3 ceramic-ZnO varistor ceramic insulators (defined as A-B-A insulators) is proposed to improve surface flashover performance in vacuum so that it is possible to reduce the electric field at the vacuum-insulator-cathode triple junction (CTJ) by changing the conductivity and permittivity of the ZnO varistor cera...
View full abstract»

The ITER tokamak (Latin for “the way”) is the next step toward the realization of electricity-producing fusion power plants, since it has been designed to reach the plasma burning condition. The Central Safety System for Nuclear Risk (CSS) is the control system in charge to assure nuclear safety for the ITER plant, the personnel, and the environment. Since the CSS is a critical safet...
View full abstract»

As one of the critical elements of fast linear transformer driver (FLTD), gas switch directly influences the output parameters, stability, and reliability of generators based on FLTD technology. In this paper, a multigap gas switch with six gaps in series has been investigated to study the proper firing conditions to get better performance for FLTD. The self-breakdown voltage with different gas pr...
View full abstract»

In this paper, the design, construction, and test procedure of a closing-switch prototype based on thyristors are described. In particular, details are given about the design criteria and the triggering board architecture, which is a high-side-biased self-supplied unit using electrical energy derived from a local snubber network for the gate drive. The structure guarantees a hard firing gate pulse...
View full abstract»

In this paper, high current vacuum arc (HCVA) characteristics and anode melting pool (AMP) flow phenomena under different conditions are researched and analyzed. Particularly, rotation phenomena of AMP are observed and analyzed. First, the influence of different arc currents on arc column and anode activities is researched. Experimental results show that the rotation phenomena of AMP become more s...
View full abstract»

This paper presents an overview of the safety-related operating feedback taken into account in the ITER baseline design and of the previously completed and ongoing research and development (R&D) activities in support of ITER safety analyses. Operating feedback relevant to ITER mostly comes from previous and currently existing fusion devices and from the operation of tritium laboratories. Regar...
View full abstract»